Biology 133 lecture AY 2021- 2022

Good day Ma'am Leonardo! Here are our answers:

1. Unfortunately, as reported by the journal article we selected and according to Copp and Green (2010, as cited in Yamaguchi & Miura, 2013), the exact mechanism as to how neural crest cells affect and contribute to normal neural tube closure still remains unclear.

2. Exencephaly can be detected by various screening tests (prenatal tests) such as ultrasound. Along with other neural tube defects, it may be identified during the 11th to 14th week gestation (Santana et al., 2018). Other tests that can indicate a neural tube defect include the quad marker screen, amniocentesis, and fetal magnetic resonance imaging (MRI). Unfortunately, there is no treatment for exencephaly once it has occurred; however, its risk can be lowered by pregnant women getting sufficient folic acid, avoiding certain medications, and managing their health (CDC, 2020; Cleveland Clinic, n.d.).


Centers for Disease Control and Prevention (2020). Facts about Anencephaly. https://www.cdc.gov/ncbddd/birthdefects/anencephaly.html
Cleveland Clinic (n.d.). Anencephaly. https://my.clevelandclinic.org/health/diseases/15032-anencephaly
Martins Santana, E. F., Araujo Júnior, E., Tonni, G., Costa, F., & Meagher, S. (2018). Acrania-exencephaly-anencephaly sequence phenotypic characterization using two- and three-dimensional ultrasound between 11 and 13 weeks and 6 days of gestation. Journal of ultrasonography, 18(74), 240–246. https://doi.org/10.15557/JoU.2018.0035
Yamaguchi, Y., & Miura, M. (2012). How to form and close the brain: insight into the mechanism of cranial neural tube closure in mammals. Cellular and Molecular Life Sciences, 70(17), 3171–3186. doi:10.1007/s00018-012-1227-7

Hello! Happy New Year as well!

To answer your question, after researching on this particular subject, there is still no conclusive answer as to why cranial neurulation defects are more common in females. However, besides the two hypotheses we have mentioned in the report, a more recent one from a study by Liu et al. (2018) states that it could be caused by a disproportionate effect of folic acid (FA) which alters the sex-specific prevalence of neural tube defects (NTDs). Folic acid is an important periconceptional supplement which dramatically reduces the risk for NTDs in offspring. In the splotch mouse strain, dietary folate deficiency exacerbates female susceptibility to exencephaly. If such case is the same in some human NTDs, it is expected that an increase in population-level folate status may have a greater effect on NTDs in women than in men. This is consistent with the findings of Liu et al. (2018) after they implemented a massive FA supplementation programme, where the prevalence of NTDs decreased to a greater degree in women than in men.

Liu, J., Xie, J., Li, Z., Greene, N., & Ren, A. (2018). Sex Differences in the Prevalence of Neural Tube Defects and Preventive Effects of Folic Acid (FA) Supplementation among Five Counties in Northern China: Results from a Population Based Birth Defect Surveillance Programme. BMJ Open. doi:10.1136/bmjopen-2018-022565